Circuit 05: Voltmeter, Variable Range

In this circuit the battery voltage can be between 2.4 V and 20 V.
The lower limit of the measured range can be between 0 V and the battery voltage.

Resistors R1 and R2 are optional for further adjustment. (bridge them if not used.)

Example

The voltage of a 12 V LiFePO4 battery can range from 10 V to 14.4 V.

We want to calibrate two potentiometers such that

• When the voltage at the BATT terminal is 14.4 V, all LED's are on
• When the voltage at the BATT terminal is 10 V, all LED's are off

Calibration Procedure